No search was conducted on the subject matter of this disclosure in the U.S. Patent and Trademark Office or in any other search facility. I am unaware of any prior art which is relevant to the subject matter disclosed and claimed in this specification.
In FIGS. 1, 2 and 3 there is illustrated a method by which I attempted to obtain an opaque screening area on the surface of a glass sheet. This particular process, however, failed for reasons which will be set out in greater detail hereinbelow.
In FIG. 1 there is seen a windshield construction prior to lamination generally identified by the numeral 10. This construction is formed of an inner glass sheet 12 and an outer glass sheet 14. The inner glass sheet 12 has an opaque screening area 16 extending around the entire perimeter thereof. The thickness of this screening area is exaggerated in the figures so that it is more readily viewable. In actuality the thickness of the screening area is about 0.001-0.002 inches.
The opaque screening area is formed by applying an opaque ceramic-containing paste in the desired pattern to the inner glass sheet 12. Thereafter, the glass sheet is heated, as, for example, in a glass bending or tempering operation, which heating causes components of the ceramic paste to react and bond themselves to the glass surface of the inner glass sheet, thereby to form the opaque screening area 16 fully bonded to the glass.
FIG. 2 shows a completed windshield construction 10 in which the inner glass sheet 12 and the outer glass sheet 14 have been laminated together by a suitable laminating interlayer in a laminating operation well known to the skilled artisan. Since laminating of glass sheets is well known, no further discussion thereof will be undertaken herein. However, the operation does provide a windshield construction which has the opaque screening area 16 extending around the entire perimeter thereof.
The opaque screening area is used to block the view of certain interior portions of a motor vehicle from the exterior of that vehicle. For example, when the windshield construction 10 is installed in a motor vehicle, the lower portion of the opaque screening area 16, that portion at the bottom of the installed windshield, generally blocks the view from the exterior of the vehicle into the area below the instrument panel of the vehicle.
In a similar manner, from inside the vehicle, the lower portion of the opaque screening area 16 blocks any front seat passenger's view of the interior of the engine compartment, which otherwise could be seen through the lower portion of the installed windshield. The side portions and upper portion of the opaque screening area 16 are effective in blocking a view of the clips and assembling devices used to fasten windshield moldings and headlinings to the interior of the motor vehicle.
Thus the opaque screening area 16 provides a means by which certain unsightly portions of the construction of the vehicle are blocked from view from persons either within or without the vehicle.
As is best understood by reference to FIG. 3, I initially attempted to develop a method of applying the ceramic-containing paste for making the opaque screening area 16 on the inner glass sheet 12 of the windshield construction in a direct silk screen printing operation. In such a case, a silk screen printing device, generally identified by the numeral 20 in FIG. 3, contained a silk screen mounted in a frame 22, the silk screen having an emulsion-containing portion 24 and a nonemulsion-containing portion 26. As is well understood in the art, the nonemulsion-containing portion of the silk screen is that portion of the screen through which paste-like materials may be printed on a surface disposed thereinbelow.
Since I was operating at the edge of the glass sheet in order to directly print the opaque screening area 16 along the perimeter of the inner glass sheet 12, I soon found that the sharp edge along the perimeter of the glass sheet rapidly abraded the nonemulsion-containing portion 26 of the silk screen, thereby rendering the silk screen useless. The abrasion would occur in less than ten printing operations, which made the entire process extremely expensive due to the high cost of continually preparing silk screens. In normal applications, silk screens should be available for use in a printing operation at least five thousand times.
In view of my initial failure in this area, I looked for a new manner of developing the opaque screening area about the perimeter of a glass sheet which is to be used subsequently, for example, in a motor vehicle.
It is a principal object of the method of this invention to apply an opaque screening area to a surface of a glass sheet in a manner which is economical to carry out and efficient in operation.